That's my picture, after testing with 60V rails and a 4 ohm dummyload, there wasn't much left of the "sanken" transistors.
😀
At least I have a nice heatsink now for 1/3 of the price they charge in the Netherlands 🙂
sayang001 said:
I think even the original sankens wouldn't survive this.
380watt rms with a single pair ?
Mike
The original MT-100 Sanken devices are quite rugged. I've tested two pairs of genuine C3264/A1295 with 84V rails [sagging to 75V during transients], driving a hybrid reflex/horn-loaded 15" 4 ohm driver [quite reactive load] with 280Hz 24dB/oct low-pass [essentially a PA LF system]
The devices survived repeated tests but I measured speaker voice coil temperatures well above 90ºC after 2 minutes of playing audio signals at full output swing. The driver was rated at only 300Wrms so it was the limiting factor for test time [I can't afford serious PA 15"/18" drivers]
[NOTE: Voice coil temperature measured indirectly trough Rdc changes. In these circumstances, a driver rated at 300Wrms would not overheat too much when operating in direct radiation, but horn loading reduces cone excursion and thus vented pole piece provides less cooling due to less air displacement inside it]
Anyway, a pair of original Sankens with reasonable heatsinking should survive 60V sagging rails and a 4 ohm load
The devices survived repeated tests but I measured speaker voice coil temperatures well above 90ºC after 2 minutes of playing audio signals at full output swing. The driver was rated at only 300Wrms so it was the limiting factor for test time [I can't afford serious PA 15"/18" drivers]
[NOTE: Voice coil temperature measured indirectly trough Rdc changes. In these circumstances, a driver rated at 300Wrms would not overheat too much when operating in direct radiation, but horn loading reduces cone excursion and thus vented pole piece provides less cooling due to less air displacement inside it]
Anyway, a pair of original Sankens with reasonable heatsinking should survive 60V sagging rails and a 4 ohm load
sayang001 said:
Change your profile Bud, Almere literatuurwijk is not Amsterdam !
Maybe you can fill your suitcase with heatsinks for your DIY homies on your next holiday.
How is Popeye doing ? I love the Pink front.
Eva said:
The Sanken's are multi-emitter transistors, i gathered the heat is spreaded more evenly within the die, the reason for them being rugged ?
Do you have more info on this kind of transistors, Eva ?
MikeB said:
Sometimes transistors are more robust than expected if the circuit is truly cross-conduction and oscillation free. I've been using for several weeks a single pair of TIP35C/TIP36C [BD249C/BD250C] to drive the same 4 ohm reactive load [Rdc=3.3] witn +-40.5V *regulated* rails and they still survive. The heatsink heats up to about 50ºC after continuous playing [LF music signal]
It features composite Vbe multiplier and the thermal negative feedback is so high that the bias allways gets reduced as temperature increases. This compensates the temperature difference betweem the dies and the heatsink. The actual bias when playing hot is 100mA [dies hotter than heatsink] while the apparent bias [dies as hot as the heatsink] is 25mA. This happens in all class-AB circuits. Bias should be allways measured when playing [temporarily muting the signal and disconnecting the load]. Idle bias measurements are useless
jacco vermeulen said:
I have no info. I only have a bunch of these transistors for experimentation and their datasheets. They feature a massive copper plate that theoretically improves pulsed SOA
Anyway, I think OnSemi TO-3 and TO-264 ones may also survive
Eva said:
I think, the mj15024 and mjl21193 should do these jobs, they
have incredibly high SOA, and the mj21193 also uses a copperplate
below the die. I don't know if the mjl also have this.
You can see the copperplates here:
An externally hosted image should be here but it was not working when we last tested it.
Mike
I got this (translated) mail from Farnell today.
"First of all, thank you for announcing the problem.
We didn’t update the database when purchasing from Magnatec instead of Toshiba.
This problem should be solved by now.
In addition, an alternative device with higher standard specifications
from ON semiconductors will be available in a complementary pair.
Our sincere apologies for this inconvenience."
-=Hugo=-
"First of all, thank you for announcing the problem.
We didn’t update the database when purchasing from Magnatec instead of Toshiba.
This problem should be solved by now.
In addition, an alternative device with higher standard specifications
from ON semiconductors will be available in a complementary pair.
Our sincere apologies for this inconvenience."
-=Hugo=-
Hi All,
Well I mailed my Magnatecs back to Farnell' on 24th Nov, but our so called Royal Mail has 'lost' them.
Farnell cannot deal with my complaint if they don't get the package !
I sent them by Recorded post and did a trace via the Internet portal. It says - this item has not been signed for therefore it cannot be traced.
Thus I have been obliged to make extra trips to the Post Office to get a form to claim, which the they would not accept back over the counter and told me I had to post to Royal Mail with all original receipts !
This is typical of living and trying to do business in todays UK, and I cannot understand why foreigners want to immigrate here. The entire place is shackled by tape that makes you see its colour - red !
Cheers .......... Graham.
Well I mailed my Magnatecs back to Farnell' on 24th Nov, but our so called Royal Mail has 'lost' them.
Farnell cannot deal with my complaint if they don't get the package !
I sent them by Recorded post and did a trace via the Internet portal. It says - this item has not been signed for therefore it cannot be traced.
Thus I have been obliged to make extra trips to the Post Office to get a form to claim, which the they would not accept back over the counter and told me I had to post to Royal Mail with all original receipts !
This is typical of living and trying to do business in todays UK, and I cannot understand why foreigners want to immigrate here. The entire place is shackled by tape that makes you see its colour - red !
Cheers .......... Graham.
Royal Mail
Graham,
I totally understand your frustration, but can assure you that the UK is not the only place in Europe where they test the limits of their citizens with ever more innovative means.
This is why I am now quite happily living in Germany, despite some difficulties as a foreigner (aren't we all when away from home). And there are a number of Brits here who share the same view.
Cheers,
Patrick
Graham,
I totally understand your frustration, but can assure you that the UK is not the only place in Europe where they test the limits of their citizens with ever more innovative means.
This is why I am now quite happily living in Germany, despite some difficulties as a foreigner (aren't we all when away from home). And there are a number of Brits here who share the same view.
Cheers,
Patrick
I know that the Magnatec are very good transistors.
A respectable Italian brand uses they.
Take a look at this site http://www.amaudio.it/
Ciao.
A respectable Italian brand uses they.
Take a look at this site http://www.amaudio.it/
Ciao.
Hi All,
Yesterday - 14th December - I received from Farnell a credit note dated 2nd Dec., which could have been applied to my more recent order of 6th Dec, but which was not !
I had requested that they forward either the Toshiba parts I had originally ordered from their catalogue, or a full refund.
As it is, they have entered 'NO LONGER REQUIRED' against my return, and then held on to my money !
Most unsatisfactory business principles.
With regard to my request for the Post Office trace;-
This has still not been acknowledged, nor do they yet have any signature for delivery of my 'Recorded Delivery' of the parts Farnell belatedly acknowledge as having been returned!
Isn't that just fantastic ???
Oh well, at least its almost Christmas.
Cheers ........ Graham.
Yesterday - 14th December - I received from Farnell a credit note dated 2nd Dec., which could have been applied to my more recent order of 6th Dec, but which was not !
I had requested that they forward either the Toshiba parts I had originally ordered from their catalogue, or a full refund.
As it is, they have entered 'NO LONGER REQUIRED' against my return, and then held on to my money !
Most unsatisfactory business principles.
With regard to my request for the Post Office trace;-
This has still not been acknowledged, nor do they yet have any signature for delivery of my 'Recorded Delivery' of the parts Farnell belatedly acknowledge as having been returned!
Isn't that just fantastic ???
Oh well, at least its almost Christmas.
Cheers ........ Graham.
A merry Christmas just the same, Graham.
I assure you that others on opposite borders experience the same sometimes, red tape is not restricted to the 25th only.
I assure you that others on opposite borders experience the same sometimes, red tape is not restricted to the 25th only.
Hi All,
Well on Saturday I received two envelopes;-
(1) My credit card statement showed that Farnell had actually refunded the parts cost to me. This is not clear from the issued 'Credit Note', and there still has not been any reply to my written complaint.
(2) A cheque arrived for the 'missing' Recorded parts that our Post Office still do not know they delivered without signature. Now I have to write another letter sending that back.
Oh for that simple life before everything became computerised. It really was far more efficient !!!
Cheers ........... Graham.
Well on Saturday I received two envelopes;-
(1) My credit card statement showed that Farnell had actually refunded the parts cost to me. This is not clear from the issued 'Credit Note', and there still has not been any reply to my written complaint.
(2) A cheque arrived for the 'missing' Recorded parts that our Post Office still do not know they delivered without signature. Now I have to write another letter sending that back.
Oh for that simple life before everything became computerised. It really was far more efficient !!!
Cheers ........... Graham.
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